This invention is generally directed to duplicating equipment of the type in which a transferable image is received on plain paper, and more particularly, relates to the use of ion modulating devices in combination with the various instrumentalities used in duplicating systems to produce a multifarious duplicator.
In the duplicator art, there are several known systems whereby a reproduction is produced on plain paper by transferring a material image from an image generating medium in a cyclic fashion so that a given processing cycle is repeated many times until the number of desired reproductions is completed.
One of the most well known of such duplicating systems is the lithographic duplicating process in which the image generating medium is a lithographic or planographic master which is differentially receptive to water and oil base inks. The lithographic master is required to be prepared as a separate step by either writing directly on the master or by photographic techniques in the circumstances that the master is light sensitive. As is well known, the lithographic process calls for applying to the cylinder mounted master both ink and water resulting in an ink or material image which is then transferred to a blanket cylinder which, in turn, is pressed against a sheet of impression paper to produce the final reproduction.
Another well-known duplicating system involves electrostatic reproduction techniques in which the image gnerating medium is a drum or cylinder on which has been applied a light-sensitive photoconductive layer which becomes imageable by well-known electrostatic reproduction techniques. Accordingly, a pattern of light and shadow is projected onto the light sensitive photoconductive drum which is then developed by the application of electroscopic powder. The electroscopic powder is transferred to plain paper, and again, there results a duplicating system whereby multiple copies may be made of a graphic original.
Derivative systems of the above described duplicating systems are known that employ these basic techniques in special ways. For example, in lithographic duplicating there is available direct lithography avoiding the use of the intermediate blanket on which the transferable image is created. In the electrophotographic systems, several variations are known which utilize the basic concept. One such system goes through a complete imaging cycle for each copy requiring charging, exposure, developing, transfer and cleaning. Another variation avoids most of these steps and utilizes a latent image reproduction in which one latent image is developed after each transfer. Still another system calls for fusing the powder image on the photoconductive layer so that it serves as the base on which is attracted the electroscopic powder on subsequent developing cycles, avoiding the photographic imaging of the photoconductive medium.
In the electrophotographic art, such duplicating systems may use replaceable photoconductive sheets so that at the end of a given cycle, the photoconductive medium may be renewed by using a new master as the electrophotographic image generating medium.
All of the aforedescribed duplicating systems have enjoyed significant commercial success but not without certain disadvantages. The main cause of such disadvantages resides in the preparation of the image generating medium. In the case of the lithographic master, it requires special preparation, using either the photographic techniques or direct imaging. In either case it requires special handling in development of the master so that it is differentially receptive to water and ink. In the case of electrophotographic systems, the photoconductive medium requires frequent replacement because these materials are fragile and are easily scratched or damaged in the normal course of usage.
There is a need in the duplicating art for a multifarious system in which there is a universal type image generating medium, hereinafter referred to as IGM, that can be utilized interchangeably with the electrophotographic techniques or the lithographic systems.